Ben-Gurion University of the Negev Faculty of Engineering Sciences Department of Industrial Engineering & Management
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BEN-GURION UNIVERSITY OF THE NEGEV FACULTY OF ENGINEERING SCIENCES DEPARTMENT OF INDUSTRIAL ENGINEERING & MANAGEMENT Momentum in Football THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE M.Sc DEGREE By: Emri Dolev March, 2020 01.03.2020 _ 1/3/2020 i Abstract: Many studies have been conducted on momentum in sports, with contrasting results and their underlying explanations debated greatly. We define momentum to be a state where success in a previous event leads to an increased likelihood of success in the next corresponding event. The initial argument regarded the validity of calling momentum by its name, with the “Hot-Hand” fallacy (Gilovich, Vallone, & Tversky, 1985) stating that the momentum that is seen and perceived is nothing but a human heuristic which allows us to see patterns, even when those patterns are random. Curiously, unlike other sporting fields, this topic has hardly been studied in the world’s most popular sport – football. As part of this study we carried out an observational, time-series analysis of both team and player levels from the elite European football leagues. We discovered evidence for the existence of momentum carried over from match to match for football forwards as a result of providing goals in their previous appearance. On a team level, only a weak momentum effect was found – which could be better attributed to the teams’ qualities. We discuss the implications of these findings and propose future directions of research that should be conducted in order to further the research of momentum in football. Keywords: Momentum, Football, Sports, Hot Hand, Mixed Logistic Regression, Statistics ii Acknowledgements I would like to express my deepest gratitude to my two academic advisors – Professor Yisrael Parmet and Professor Miki Bar-Eli for helping to guide me through the process of writing this thesis. From our very first meeting together, you have been nothing but supportive and have been equally inspirational and motivational for me. I have thoroughly enjoyed our shared meetings, and the different topics and discussions that have arisen. At times these discussions could sway off-topic in relation to the subject-matter of this thesis, but none-the-less they were truly stimulating and fascinating. I could not have completed the writing of this thesis without your directions, whether Miki on the theoretical side or Yisrael on the methodological side. Thank you both so much for being excellent advisors to me. I would also like to thank my family, especially my parents. I am so lucky and grateful to have such a supportive foundation that I can always count on and lean on to raise my spirits during hardships, but also to bring me down to earth when a little perspective is required. You have given me so much, even when I may not have deserved it or not known to appreciate it appropriately. You have provided me a full and plentiful life thanks to your hard work and love. I cannot put into words how much you both mean to me, and I do not say it enough – I love you . Thank you for everything. iii Table of Contents Abstract (English) i Acknowledgements ii 1 Introduction 1 1.1 Motivation . 1 1.2 Theoretical Background . 3 1.2.1 Momentum in Sport . 4 1.2.2 “Hot Hand” Phenomenon . 8 1.2.3 Self-Efficacy . 18 1.2.4 Self-Efficacy, Psychological Momentum, Performance and Success 23 1.2.5 Psychological Momentum and “Hot Hand” Research in Football . 31 1.3 Research Outline . 35 1.3.1 Research Questions . 36 1.3.2 Research Scope . 36 1.3.3 Project Outline . 37 2 Method 38 2.1 Data Sources . 39 2.2 Data Description . 39 2.2.1 Player-Level . 39 2.2.2 Team-Level . 42 2.3 Data Engineering . 44 2.3.1 Player-Level Data Engineering . 44 2.3.2 Team-Level Data Engineering . 54 2.4 Prepared Data . 72 2.5 Statistical Model . 73 2.5.1 Model Definition . 75 2.5.2 Model Selection . 76 3 Results 78 3.1 Player-Level Analysis . 78 3.1.1 Scoring a Goal is Considered a Success . 78 3.1.2 Scoring or Assisting a Goal is Considered a Success . 83 3.1.3 Mediation of Relationship by Minutes Played . 88 iv 3.2 Team-Level Analysis . 91 3.2.1 Winning Equals Success – with Teams’ Quality Gap . 91 3.2.2 Winning Equals Success – without Teams’ Quality Gap . 93 3.2.3 Comparison of the Team-Level Models . 96 4 Discussion 98 4.1 Player-Level . 99 4.1.1 Mediation by Minutes Played . 100 4.2 Team-Level . 101 4.3 Future Research . 103 4.4 Practical Application . 105 4.4.1 Comparison of Forwards Across Different Eras . 105 4.4.2 Scouting . 106 4.4.3 Managers’ Press Conference . 106 4.4.4 Man Management . 106 4.4.5 Story-Telling of Sports . 107 Appendices 108 The 95th Percentile of Scorers in the “Top-5” European Football A 108 Leagues. B Historical Forward Legends of Football . 110 Teams that Played in “Top-5” European Football Leagues from C 111 2000-2019 . References 114 Abstract (Hebrew) 120 1 Chapter 1 Introduction 1.1 Motivation There is a common notion of momentum in the world of sports, in which both players and teams can reach peaks of form that are driven by an enhanced psychological state as a result of their previous successful performances. This perception of momentum that drives future success is at the heart of this study as we set out to investigate whether it is grounded in empirical evidence, or simply an illusion conceived by the human imagination that has been imprinted into our narratives when discussing sports. This belief in momentum is held at both a player-level, where a single athlete has their own momentum based on their personal performances and experiences, and also at a team-level where collective momentum is developed based on a team’s collective performances and experiences. A team’s recent form is a central part of the conversation whenever commentators are previewing an upcoming match (“this team is coming into this match on the back of good/poor form”), or reviewing the outcome of a completed match (“this team is continuing its rich/dreadful vein of form”). Teams’ form is also a central statistic in the betting industry, with a visualization of a team’s recent results often being displayed to potential gamblers as part of the information provided to them regarding upcoming matches. Yet, the most famous example of this observed momentum in sports is the “hot hand” phenomenon – a basketball player taking a shot is considered to be more likely to score if their recent previous shots were successful, and they are therefore considered to be in a 2 “hot streak” of scoring. Generally speaking, ”the belief is that the performance of a player during a particular successful period is significantly better than expected on the basis of the players’ overall record” (Gilovich, Vallone, & Tversky, 1985). This belief also holds true in the world’s most popular sport, football, and is shared by commentators, spectators , players, and coaches/managers alike. The belief of momentum at a player-level is exemplified by former Manchester United manager Sir Alex Ferguson’s explanation of an apparent “dip” in the form of Wayne Rooney, England’s all-time top international goalscorer in 2010. “I say it time and time again; strikers live by their goals. When they are not scoring, they think the goals are never going to come. Then, when they do come, they think they are never going to finish. That is normal with any forward.” (The Telegraph, 2010). Forwards in football are unique because they are tasked with the responsibility of providing the goals for their teams which are crucial in leading their teams to win. Extended periods of matches where forwards play without scoring have been termed “goal-droughts” by the media – an unproductive period that practically every top forward in the game has endured during their career, and is often a central talking point during managers’ press conferences. Examples of top football managers’ belief in momentum when asked about their forward’s goal-droughts are plentiful. When asked about Romelu Lukaku’s goal drought in 2018, Jose Mourinho, one of the most successful managers in recent years replied, “Not just with the goals he is not scoring but also in his confidence, in his movement, his touch,” Mourinho told reporters after a defeat, “He is not linking the game well with the team. But he is our striker and he is a good striker we believe in. Romelu is a hard- working guy and a good professional. One day the goals will arrive and the confidence will be back.” (Reuters, 2018) 3 Sir Alex Ferguson, widely considered to be one of the greatest football managers of all- time due to his success and longevity, was the subject of a case study of his methods (Elberse, 2013). Eight leadership lessons that captured the central elements of Ferguson’s managerial approach were outlined, and two of these leadership lessons are of major relevance to this research; (a) to match a message to the moment, (b) to rely on the power of observation. As part of this study, our intention is to investigate whether momentum exists in football. We will rely on statistical modelling of historical observations to investigate the idea that teams and/or forwards are affected by their recent “form”. Our aim is to discover if this perception of momentum is grounded in statistical significance or not – is there empirical evidence for its existence in football; perhaps managers simply attempt to instil confidence in their forwards during these goal-droughts by matching a message for them during their moments of poor “form”, perhaps teams do not develop collective momentum and the pundits, coaches, and supporters alike all subconsciously see artificial patterns in teams’ recent results which they mistakenly attribute to “form”.